arch/alpha/include/asm/percpu.h

   1 #ifndef __ALPHA_PERCPU_H
   2 #define __ALPHA_PERCPU_H
   3
   4 #include <linux/compiler.h>
   5 #include <linux/threads.h>
   6 #include <linux/percpu-defs.h>
   7
   8 /*
   9  * Determine the real variable name from the name visible in the
  10  * kernel sources.
  11  */
  12 #define per_cpu_var(var) per_cpu__##var
  13
  14 #ifdef CONFIG_SMP
  15
  16 /*
  17  * per_cpu_offset() is the offset that has to be added to a
  18  * percpu variable to get to the instance for a certain processor.
  19  */
  20 extern unsigned long __per_cpu_offset[NR_CPUS];
  21
  22 #define per_cpu_offset(x) (__per_cpu_offset[x])
  23
  24 #define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
  25 #ifdef CONFIG_DEBUG_PREEMPT
  26 #define my_cpu_offset per_cpu_offset(smp_processor_id())
  27 #else
  28 #define my_cpu_offset __my_cpu_offset
  29 #endif
  30
  31 #ifndef MODULE
  32 #define SHIFT_PERCPU_PTR(var, offset) RELOC_HIDE(&per_cpu_var(var), (offset))
  33 #define PER_CPU_ATTRIBUTES
  34 #else
  35 /*
  36  * To calculate addresses of locally defined variables, GCC uses 32-bit
  37  * displacement from the GP. Which doesn't work for per cpu variables in
  38  * modules, as an offset to the kernel per cpu area is way above 4G.
  39  *
  40  * This forces allocation of a GOT entry for per cpu variable using
  41  * ldq instruction with a 'literal' relocation.
  42  */
  43 #define SHIFT_PERCPU_PTR(var, offset) ({                \
  44         extern int simple_identifier_##var(void);       \
  45         unsigned long __ptr, tmp_gp;                    \
  46         asm (  "br      %1, 1f                        \n\
  47         1:      ldgp    %1, 0(%1)                     \n\
  48                 ldq %0, per_cpu__" #var"(%1)\t!literal"         \
  49                 : "=&r"(__ptr), "=&r"(tmp_gp));         \
  50         (typeof(&per_cpu_var(var)))(__ptr + (offset)); })
  51
  52 #define PER_CPU_ATTRIBUTES      __used
  53
  54 #endif /* MODULE */
  55
  56 /*
  57  * A percpu variable may point to a discarded regions. The following are
  58  * established ways to produce a usable pointer from the percpu variable
  59  * offset.
  60  */
  61 #define per_cpu(var, cpu) \
  62         (*SHIFT_PERCPU_PTR(var, per_cpu_offset(cpu)))
  63 #define __get_cpu_var(var) \
  64         (*SHIFT_PERCPU_PTR(var, my_cpu_offset))
  65 #define __raw_get_cpu_var(var) \
  66         (*SHIFT_PERCPU_PTR(var, __my_cpu_offset))
  67
  68 #else /* ! SMP */
  69
  70 #define per_cpu(var, cpu)               (*((void)(cpu), &per_cpu_var(var)))
  71 #define __get_cpu_var(var)              per_cpu_var(var)
  72 #define __raw_get_cpu_var(var)          per_cpu_var(var)
  73
  74 #define PER_CPU_ATTRIBUTES
  75
  76 #endif /* SMP */
  77
  78 #ifdef CONFIG_SMP
  79 #define PER_CPU_BASE_SECTION ".data.percpu"
  80 #else
  81 #define PER_CPU_BASE_SECTION ".data"
  82 #endif
  83
  84 #ifdef CONFIG_SMP
  85
  86 #ifdef MODULE
  87 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  88 #else
  89 #define PER_CPU_SHARED_ALIGNED_SECTION ".shared_aligned"
  90 #endif
  91 #define PER_CPU_FIRST_SECTION ".first"
  92
  93 #else
  94
  95 #define PER_CPU_SHARED_ALIGNED_SECTION ""
  96 #define PER_CPU_FIRST_SECTION ""
  97
  98 #endif
  99
 100 #define PER_CPU_ATTRIBUTES
 101
 102 #endif /* __ALPHA_PERCPU_H */